In the Firmware Upgrade document "How to upgrade firmware for DR111.pdf" the max. size of the SD card is said to be 8 GB.

My DR111 (SW:790, HW: DR111v4.1 REV A) also tends to freeze sometimes after logging: Radio to Stand-by, take out the SD card, switch on the DR111, change frequency by pressing the pre-sets and suddenly nothing works, including the Stand-by switch. Pull the DC cord and insert it again and the radio works normally (until the next hang-up).